The equipment used in the food processing industry varies by segment with the three leading segments comprising meat and poultry, beverages, snack foods, vegetables and dairy. While the equipment varies from segment to segment, the moving parts such as bearing, gears and slide mechanisms are similar and often require lubrication. The lubricants most often used include hydraulic, refrigeration and gear oils as well as all-purpose greases. These food industry oils must meet more stringent standards than other industry lubricants.
Due to the importance of ensuring and maintaining safeguards and standards of quality for food products, the food industry must comply with the rules and regulation set forth by the United States Department of Agriculture (USDA). The Food Safety Inspection Service (FSIS) of the USDA is responsible for all programs for the inspection, grading and standardization of meat, poultry, eggs, dairy products, fruits and vegetables. These programs are mandatory, and this inspection of non-food compounds used in federally inspected plants is required.
The FSIS is custodian of the official list of authorized compounds for use in federally inspected plants. The official list (see page 11-1, List of Proprietary Substances and Non-food Compounds, Miscellaneous Publication Number 1419 (1989) by the Food Safety and Inspection Service, United States Department of Agriculture) states that lubricants and other substances which are susceptible to incidental food contact are considered indirect food additives under USDA regulations. Therefore, these lubricants, classified as either H-1 or H-2, are required to be approved by the USDA before being used in food processing plants. The most stringent classification, H-1 is for lubricants approved for incidental food contact. The H-2 classification is for uses where there is no possibility of food contact and assures that no known poisons or carcinogens are used in the lubricant. The instant invention pertains to an H-1 approved lubricating oil. H-1 approved oil and the terms "food grade" will be used interchangeably for the purpose of this application.
In addition to meeting the requirements for safety set by federal regulatory agencies, the product must be an effective lubricant. Lubricating oils for food processing plants should lubricate machine parts, resist viscosity change, resist oxidation, protect against rusting and corrosion, provide wear protection, prevent foaming and resist the formation of sludge in service. The product should also perform effectively at various lubrications regimes ranging from hydrodynamic thick film regimes to boundary thin film regimes.
The oxidation, thermal and hydrolytic stability characteristics of a lubricating oil helps predict how effectively an oil will maintain its lubricating properties over time and resist sludge formation. Hydrocarbon oils are partially oxidized when contacted with oxygen at elevated temperatures for prolonged periods of time. The oxidation process produces acidic bodies within the lubricating oil which are corrosive to metals often present in food processing equipment, and in contact with both the oil and the air are effective oxidation catalysts which further increases the rate of oxidation. Oxidation products contribute to the formation of sludges which can clog valves, plug filters and result in overall breakdown of the viscosity characteristics of the lubricant. Under some circumstances, sludge formation can result in pluggage, complete loss of oil system flow and failure or damage to machinery.
The thermal and hydrolytic stability characteristics of a lubricating oil reflect primarily on the stability of the lubricating oil additive package. The stability criteria monitor sludge formation, viscosity change, acidity change and the corrosion tendencies of the oil. Hydrolytic stability assesses these characteristics in the presence of water. Inferior stability characteristics result in a lubricating oil that loses lubricating properties over time and precipitates sludge.
It is, therefore desirable to provide an improved food grade lubricating oil which overcomes most, if not all of the proceeding problems.
U.S. Pat. No. 3,776,847 (Pearson et al, Dec. 4, 1973) relates to a lubricating oil composition suitable for the hot rolling of metals, in particular ferrous metals such as steel. The reference further relates to a process for the hot rolling of metals use the lubricating oil compositions as such or as aqueous dispersions and to metal worked by means of the process. The lubricating oil compositions comprise (a) from about 50 to about 85% by weight of a natural fatty oil, (b) from about 0.1 to about 10% by weight of a basic alkaline earth metal salt of an oil soluble petroleum sulfonic acid and (c) from about 5 to about 49.9% by weight of a mineral lubricating oil having a viscosity index of at least 50.
U.S. Pat. No. 3,929,656 (Flis, Dec. 30, 1975) relates to drawing oils that comprise a major portion of a mineral oil of suitable viscosity, from about 5 to 30 weight percent of an additive from the class consisting of vegetable oils and fatty acids and from about 3 to 15 weight percent of a chlorinated paraffin containing greater than 40 percent chlorine.
U.S. Pat. No. 3,953,179 (Souillard et al, Apr. 27, 1976) relates to a lubricating composition for 2 stroke engines which comprises 90 to 97% by weight of a lubricating mixture comprising 15 to 80% by weight of a polymer selected from the group consisting of hydrogenated and non-hydrogenated polybutene, polyisobutylene and mixtures thereof, having a mean molecular weight ranging from 250 to 2000, and 0.5 to 10% by weight of a triglyceride of an unsaturated aliphatic acid containing 18 carbon atoms, the remainder of said mixture being a lubricating oil, and 3 to 10% by weight of lubricating oil additives for 2-stroke engines.
U.S. Pat. No. 4,062,785 (Nibert, Dec. 13, 1977) provides a lubricant composition which is non-toxic and therefore non-contaminating with respect to food and water. The lubricant comprises a major proportion of white oil and a minor proportion of a fatty amide. Neither of these components is toxic so that the lubricant is compatible with the human diet, the fatty amine possesses the necessary quality of lubricity which is imparted in sufficient quantity to the white oil to render the lubricant satisfactory for the lubrication of industrial devices.
The lubricant composition may also desirably contain a fatty triglyceride such as lard oil or olive oil. The triglyceride, while not as effective a lubricity additive as the fatty amine, nevertheless supplies additional lubricity to the combinations of the fatty triglyceride range up to about 10 percent.
U.S. Pat. No. 4,073,412 (Doumani, Feb. 14, 1978) provides a freeze-thaw stable, water-in-oil emulsion composition of lecithin adapted for aerosol delivery onto cookware for cooking surface lubrication, the composition consisting essentially per 100 parts by weight of (a) an organic phase free of liquid alkanes having a specific gravity below 0.75, which phase comprises in proportions to provide to the composition an acid number not higher than 12: from 1 to 10 parts of a lecithin having an acid number between about 24 and 34; from. 0 to about 8 parts of a vegetable oil having an acid number less than about 1; from about 1 to 12 parts of a mineral oil having a specific gravity above 0.80; and an emulsifying-effective amount of an edible fatty acid ester emulsifier having an acid number not higher than 15; and (b) up to 85 parts of an inorganic phase comprising the balance to 100 parts of the composition, which inorganic phase comprises water. The mineral oil specific gravity may range from 0.83 to 0.91 and range from light to heavy to have a viscosity of 50-60 SUS to as high as 450 SUS or more at 100.degree. F.
U.S. Pat. No. 4,663,061 (Kuwamoto et al, May 5, 1987) relates to a metal working oil composition containing
(A) one or more lube oil components selected from the group consisting of oils, fats, mineral oils and fatty acid ester,
(B) a cationic or amphoteric water-soluble polymer compound having a molecular weight of 1,000 to 10,000,000 and containing nitrogen atoms in the molecule, and
(C) a surfactant.
U.S. Pat. No. 4,753,742 (Wilhelm, Jr., Jun. 28, 1988) relates to a lubricant having improved lubricating and protective properties for bread dividers and the like. The lubricants consist essentially of 1% to 99% mineral oil suitable for food processing equipment applications and 1% to 90% lecithin, and have a minimum viscosity of 60 S.U.S. at 100.degree. F. Other embodiment of the lubricant also contain from 1% to 20% nonionic surface active emulsifying agents. Vegetable oils may also be added to comprise from 1% to 80% of the lubricant.
U.S. Pat. No. 4,783,274 (Jokinen et al, Nov. 8, 1988) is concerned with an anhydrous oily lubricant, which is based on vegetable oils, which is substituted for mineral lubricant oils, and which, as its main component, contains triglycerides that are esters of saturated and/or unsaturated straight-chained C.sub.10 to C.sub.22 fatty acid and glycerol. The lubricant is characterized in that it contains at least 70 percent by weight of a triglyceride whose iodine number is at least 50 and no more than 125 and whose viscosity index is at least 190. As its basic component, instead of or along with the triglyceride, the lubricant oil may also contain a polymer prepared by hot polymerization out of the triglyceride or out of a corresponding triglyceride. As additives, the lubricant oil may contain solvents, fatty acid derivatives, in particular their metal salts, organic or inorganic, natural or synthetic polymers, and customary additives for lubricants.
U.S. Pat. No. 4,828,727 (McAninch, May 9, 1989) provides a lubricant for use with a conveyor in a meat packing plant meeting the requirements of (1) adequate lubricity, (2) "drip resistance," (3) safety, i.e., approval of the composition and its ingredients by the USDA, (4) rust resistance, (5) economy of manufacture and use and (6) the ability to be removed by cleaning methods is provided by preparing a mixture of mineral oil, a fatty acid and a polybutene, each being acceptable for incidental contact with food, in certain minimum amounts and increasing the amounts of one or more of said components such that the improved lubricant has a viscosity of 20-160 centipoise.
U.S. Pat. No. 4,957,651 (Schwind, Sep. 18, 1990) relates to lubricants comprising a partial fatty acid ester of a polyhydric alcohol and a cosulfurized mixture of 2 or more reactants selected from the group consisting of (1) at least one fatty acid ester of a polyhydric alcohol, (2) at least one fatty acid, (3) at least one olefin and (4) at least one fatty acid ester of a monohydric alcohol to provide a synergistic effect.
U.S. Pat. No. 5,034,144 (Ohgake et al, Jul. 23, 1991) relates to lubricating oil compositions favorably used for food processing machines. The oil compositions exhibit highly improved oxidation stability, wear resistance and rust prevention. Raw materials quite harmless to human bodies can be used in the production of said lubricating oil composition which comprises (I) as the base oil, a saturated fatty acid glyceride represented by the following general formula ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 are each a straight chain alkyl group and (II) as an essential component, a fatty acid in an amount of 0.001 to 5% by weight, based on the total composition.
U.S. Pat. No. 5,185,091 (Ohgake et al, Feb. 9, 1993) relates to a greasy oil and fat composition for food processing machines. The composition is prepared by mixing a fatty acid ester of polyglycerol, oil and fat for food and glycerol, melting the mixture by heating and kneading the mixture.